Toasted blood glue base



l 0 6 9 CROSS REFERENCE ExAIvIII IIO June 25, 1963 c. N. coNE 3,

TOASTED BLOOD GLUE BASE Filed Oct. 31. 1960 1 2 Sheets-Sheet 1 FIGURE I POWDERED SOLUBLE BLOOD mm mm Io To Ioo% BY WEIGHT (0N may Ewan) OF SOLID FILLER IN PARTICLE FORM INsuRE THAT THE RESULTING MIXTURE HAS A MoIsTuRE coNTENT OF 2 To 35 COOL AT A TEMPERATURE OF BELOW I7oF.

MIX wITH WATER- AND GLUE-MAKING cI-IEIvIIcALs, Le.

ALKALI METAL HYDROXIDE AND PREFERABLE ALKALI METAL SILICATE AND OR LIME WITH OR WITHOUT ADDED THE MOSETTING: RESIN FINISHED GLUE CHARLES N. CONE INVENTOR.

BY Sim:

June 25, 1963 c. N. coNE 3,095,313

TOASTED BLOOD GLUE BASE Filed Oct. 31, 1960 2 Sheets-Sheet 2 FIGURE .Il

POWDERED SOLUBLE BLOOD MIX WITH 0.5 T0 Io% 5v WEIGHT (ON DRY B ooD) OF AN ALKALINE EARTH METAL CARBONATE HEAT THE MIXTURE ATA MOISTURE CONTENT 0F 2 TO 35 BY WEIGHT AND A TEMPERA uRE ABOVE I-ro" F. UNTIL THE 5LOOD Is SUBSTANTIALLY DENATURE'D COOL MIx WITH FILLER, WATER AND GLUE-MAKING CHEMICALS Le. ALKALI METAL HYDROXIDE AND PREFERABLE ALKALI METAL sILIcATE AND/OR LIME WITH OR WITHOUT ADDED THERMO- SETTING RESIN FINISHED GLUE CHARLES N. CONE INVENTOR.

United States Patent 3,095,313 TOASTED BLOOD GLUE BASE Charles N. Cone, Portland, 0reg., assignor to Pac fic Resins & Chemicals, Inc., Seattle, Wash., a corporation of Washington Filed Oct. 31, 1960, Ser. No. 76,384 7 Claims. (Cl. 106-124) This invention relates to a novel toasted blood glue base which, when compounded into a glue, is particularly applicable for uniting wood veneers in the manufacture of plywood, although it is useful in divers other apphcatio The present application is a continuation-in-part of the prior application Serial No. 846,628, filed October 15, 1959, which in turn, is a continuation-in-part of my prior application Serial No. 453,105, filed August 30, 1954, and now abandoned.

Two grades of blood, soluble and insoluble, are available commercially for use as raw materials in the manufacture of glues. Soluble blood is prepared by drying fresh blood without coagulating it, usually by spraying the blood into a stream of air heated to such a temperature that the blood dries before it has time to coagulate. As the name implies, the product is soluble, or at least dispersible, in aqueous media. Insoluble blood is prepared by heating or otherwise treating fresh blood to coagulate it, after which it is dried and ground. This product is not soluble in water and ordinarily is used for feed or fertilizer.

In my United States Patent 1,976,436, there is disclosed a blood glue comprising luble blood mixed at normal temperatures with caustic ails ,hydrated lime andsodiumsilicate, While this glue is useful for some purposes; it is subject to a pronounced tendency to become too viscous for use and to gel when used in conventional glue spreading apparatus. As a result, it has never been used commercially except in admixture with at least an equal amount of other adhesive materials such as soybean flour and casein, which to some extent mask or control its undesirable viscosity and spreading properties.

In my United States Patent 2,400,541, a glue is described which is made from fertilizer grade, insoluble, coagulated blood, the primary purpose of the invention being to convert this abundant, relatively inert, dried product to a usable glue. The process employed consists of heating the blood in aqueous alkaline medium at a temperature of preferably between 180 F. and the boiling point of the medium. This hydrolyzes or otherwise acts upon the blood and causes it to swell, soften, and disperse until it becomes a relatively homogeneous, viscous mass. The hydrolyzed blood then is cooled to approximately room temperature after which glue conditioning agents including additional alkali, lime and sodium silicate are added to form the final glue mixture.

The above glue also is useful in some applications, but its preparation is attended by the serious difiiculty that the mixture resulting from cooking the blood with alkali rapidly gels and becomes thick upon cooling. As a result, it is impossible to secure effective heat transfer between the cooling medium and the glue mixture. This, in turn, extends to many hours the period of time required to bring the mixture down to room temperature, which has apparent disadvantages in loss of time and the necessity of using elaborate cooling equipment.

In my United States Patent 2,895,928, issued July 24, 1959, there is disclosed a blood glue made from either fresh blood or the soluble blood of commerce. It is made by coagulating the blood in dispersed form in an aqueous medium by increasing the temperature of the blood to above 120 F. while agitating it for maintaining the coagulated blood particles in finely divided condition and dispersed throughout the aqueous blood medium. The resulting aqueous dispersion of coagulated blood then is cooled to a temperature of below F. after which the resulting glue base is converted to a commercial glue by the addition of one or more glue-making chemicals, i.e., glue conditioning agents, including alkali metal hydroxide, preferably with added alkali metal silicate, and/or lime and, if desired, a thermosetting resin.

The glue made by the latter procedures has had substantial commercial success. Its manufacture and use are, however, attended by certain significant disadvantages. It has some tendency to gel. Its viscosity is such that the amount of water which may be added to it is limited, increasing correspondingly the cost of the glue. The ratio of water to blood in the glue is not adjustable over as wide a range as is desirable to produce a range of glue products suitable for various applications. The procedure for coagulating the blood is relatively time consuming, requires relatively elaborate equipment, and consequently is relatively costly. Since ordinarily preliminary to the coagulating procedure dry soluble blood is introduced into water, a sticky mass having a tendency to lump may be formed, requiring that special precautions be taken.

Still further, the difi'iculty is present that if the blood is coagulated at a central location for distribution to the plywood plants which use it, the transportation costs are high, since the blood contains such a large proportion of water. On the other hand, if it is desired to overcome this difiiculty by coagulating the blood at the plywood plant, special equipment is required which ordinarily is not available. Also, since the proper coagulation of the blood is critical to the success of the final glue, skilled supervision of the coagulating procedure is required. This is particularly true since various sources of blood are used and the coagulating properties of the blood obtained from these sources vary substantially.

However, the most significant disadvantage characterizing the blood glues of US. Patent 2,895,928 resides in the fact that they have to be mixed immediately before use by the .plyvyo od n arruiacturer at his plant, unsupervised by the glue manufacturer. This procedure required skilled personnel of a class not always available. This disadvantage stems from the fact that after the soluble blood has been coagulated in aqueous medium, addition of the glue-making (conditioning) chemicals, including ,alkali"'' metal hydrox i dg alkalimetalgsf ma rodumliigh droi sis of the blgpg. Also, the blood is subject to putielactiifiqfirffig s tbrage and shipment unless serious elioits are made to preserve it.

Accordingly, it is the general object of this invention to provide a blood glue and process for making the same wherein the glue base may be prepared by the glue maker at a central location and shipped dry to the mills where it is mixed with the glue-making chemicals, resulting in the formulation of a glue of superior properties.

In accordance with one form of the presently described process, powdered soluble blood is mixed with f 10% 59". based on the weight of t lffify blood, of apowdered solid filler. Next, the moisture content of the resultiii g mix'ffiie'isadjusted, if necessary, to insure a moisture content of from 2% to 35%. The solid mixture of controlled moisture content next is heated with agitation for denaturing the blood.

I have further found that an econo ay be obtained by pretreating soluble blood powder with a minor proportion, i.e., from 0.5% to 10% b Wei ht based on the dry blood, of a carBonaie of an alkaline earth meta u a powdery product. When the blood is mixed with this material, even in small amounts, the powder coats over the surfaces of the individual blood particles so that upon subsequent application of heat the particles remain separate, or form friable aggregates which may easily be reduced to the form of denatured blood particles. This result, using finely divided earth metal carbonate enables heating and handling of a smaller proportion of filler material.

Although the reactions occurring during the heating operation are not capable of precise definition, the blood is denatured to form a product which is different from that obtained by coagulating blood in aqueous medium. Thus, the denatured product is substantially insoluble in water. However, it retains a substantial solubility in a dilute aqueous solution of alkali metal hydroxide at a temperature of less than 100 F.

After denaturing the grainy, solid mass is cooled to a temperature of below 170" F., preferably below 120 F. This forms the glue base, which may be shipped dry to the desired plant destination. There it is mixed with water and the selected glue-making chemicals in the selected proportions. This results in the formulation of the finished glue.

Hence it will be seen that the process disclosed herein differs essentially from that set forth in my aforesaid United States Patent 1,976,436, in that in the process of the patent the soluble blood is used throughout in aqueous medium and no attempt is made to coagulate it. To the contrary, coagulation of the blood base material specifically is avoided, whereas in the instant application the blood base material is denatured in the dry state prior to the incorporation of the conditioning chemicals.

Also, the process disclosed herein differs fundamentally from that disclosed in my aforesaid patent, U.S. 2,400,541, in that the process of the latter employs dried, insoluble or coagulated blood as the base material and uses a caustic alkali treatment at elevated temperature as a means of dispersing the blood and dissolving it in an aqueous medium. In the present process, on the other hand, soluble blood is used as the starting material. This is denatured in the solid or dry condition. The resulting denatured solid product then is used as the glue base and is mixed with the glue-making chemicals.

.Still further, the presently described process differs fundamentally from that disclosed in my U.S. application Serial No. 461,947, in that in the process disclosed in the latter, soluble blood is placed in aqueous medium and then coagulated by the application of heat. After heating, the aqueous suspension of coagulated blood particles is cooled and mixed with the glue-making chemicals, water being present at all times as the conveying or suspending medium. 50

In the process of this invention, on the other hand, the soluble blood is denatured by the application of heat to solid blood having a certain stipulated moisture content, this being substantially less than the amount required to dissolve or disperse the blood. The resulting solid product 55 then forms the glue base which may be converted to a commercially useful adhesive by the addition of gluemaking chemicals sllchwwwm" ably---with-added alkali metalsilicate, and/or ime, with or without the addition of a theifirosettingm 60 Considering the procedure of this invention in greater detail, and with particular reference to the drawings, consisting of FIGURES 1 and 2, each being a flow plan of the presently described process:

The blood which is employed as the starting material 65 for the process of this invention comprises, as has been stated above, the spray dried, soluble blood of commerce. This is obtainable in the form of a powder of varying particle size. In general, however, a finely divided product should be employed, i.e., one having a particle size of 7 less than 20 mesh, preferably less than 100 mesh, U.S. Sieve Series. If blood having too large a particle size is used, the subsequent denaturing process is non-uniform and the glue will contain swolien blood particles of such a size as to impair its spreading characteristics.

The soluble blood starting material first is mixed with a powdered solid filler. The addition of such a filler is required since the blood is heated in powdered form. Consequently, if the filler is not added, the present techniques for heating and denaturing the blood causes it to cake and to stick to the walls of the vessel in which it is contained. In addition, the presence of the filler materially accelerates the denaturing operation.

The amount of organic filler to be used varies from 10% to preferably from 20% to 60% by weight, dry blood basis. Generally, if less than 10% by weight is employed, the blood sticks to the containing vessel to such an extent that the denaturing operation cannot be carried out effectively. However, if more than 100% by weight is used the adhesive qualities of the resulting glue are materially impaired, so that an inferior bond is obtained.

A wide variety of fillers may be used, either organic or inorganic, provided they do not degrade the blood. As examples of organic fillers, there may be cited soybean flour and similar powdered vegetable material, powdered insoluble blood, and the cellulosic fillers such as wood flour, walnut shell flour, powdered bark and selected mechanical fractions of powdered bark. Diatomaceous earth, powdered clays and talc are examples of suitable inorganic fillers. Although the particle sizes of the filler is variable, it should be finely divided, having a particle size of less than 20 mesh, preferably less than 100 mesh, U.S. Sieve Series.

When the soluble blood starting material is mixed with a myldegy carhona te of an alkaline earth metal, i.e., of calcium, magnesium, barium or strontium, a lesser proportion of filler, i.e., from 0.1% to 10% by weight may be used. Of these, calicum carbonate is preferred because of its effective action and availability.

The cgrbonatematerial should be in finely divided form, having a 'r nesh size of through 200 mesh or smaller, preferably less than 325 mesh U.S. Sieve Series. An eminently suitable carbonate material is commercial precipitated calcium carbonate having a particle size of from .04 to .05 micron.

It also is essential for the success of the presently described process that the moisture content of the mixture of blood and filler be maintained at a level of from 2% to 35% by weight, preferably from 6% to 20% by weight, based on the dry weight of the mixture. If less than this amount of moisture is present, the denaturing operation takes place very slowly, too slowly to be practical. However, if more than this amount of moisture is present, the mixture cakes excessively on heating, cannot be handled satisfactorily, and produces a glue having poor spreading characteristics.

In addition, there is a tendency to degrade the blood extensively, particularly with long denaturing durations. Adjustment of the moisture content of the mixture may be accomplished in any desired way, as by drying the raw materials before mixing them, or by adding moisture to them, as required.

Next the blood-filler mixture of controlled moisture content is heated to denature the blood. This operation may be efiectuated in any suitable equipment wherein means are provided for agitating the blood while heating it uniformly. Thus, it may be carried out in a steam jacketed cylinder provided with rotating scraper blades which prevent the blood from adhering to the interior of the cylinder and at the same time agitate it effectively. Also, it may be carried out in apparatus comprising a cylinder containing a pair of hollow, steam heated, inter-locking screws which agitate the blood while heating it and advancing it the length of the cylinder.

The dry powdered soluble blood in admixture with solid filler is denatured by heating the mixture at a temperature between F. and 350 F. for so long a time as its moisture content d ctates. Such heating to produce satisfactory denaturation normally will extend from A to 3 hours.

It will be appreciated that in view of the diverse sources of the soluble blood of commerce, the various conditions of spray drying to which it has been subjected, the length of time it has been stored, the nature and particle size and relative proportion of filler employed, the moisture content of the mixture, etc. make it extremely difiicult to set arbitrary limits on the time and temperature required for denaturing the blood according to the presently described procedure.

Whatever the apparatus employed, the blood is heated until it is denatured suflicieutly to produce a satisfactory glue base. This is accomplished when the denaturing operation has proceeded to such an extent that the blood has been rendered substantially insoluble in water. This may be determined by placing a sample of the denatured product in water and noting whether coloring of the water occurs. If the coloring produced by the introduction of the blood is not substantial then it has been denatured to the desired extent.

If the blood is insufiiciently denatured a satisfactory glue is not obtained because it will have the defects noted above as being characteristic of the blood glue described in my United States Patent 1,976,436. Also, it cannot be used at the high water content characterizing the glue of the present invention.

It is also necessary that the blood not be over denatured. If this is the case, the addition of the glue-making chemicals at a later stage is not effective in swelling and softening the blood granules and dispersing the blood as required to provide a satisfactory glue. Accordingly, the denaturing operation should be carried on only to such an extent that the blood retains substantial dispersibility in cold, dilute aqueous alkali metal hydroxide, i.e., alkali metal hydroxide at a temperature of less than 100 F.

Although insofar as is known by me, no test standards are available for measuring the dispersibility of a blood glue base in alkali, substantial solubility in aqueous alkali metal hydroxide, as defined herein, is obtained when the blood passes the following test procedure, which represents an appropriate modification of the test procedure advanced by the Armour Co., of Chicago, Illinois, for determining the water solubility of blood.

A sample containing ten grams of blood and having a moisture content of about is placed in 100 cubic centimeters of 0.2% sodium hydroxide at a temperature of from 60 to 80 F. The resulting mixture is stirred for one hour and then permitted to stand for an additional hours. At the end of this time it is stirred and filtered. For the present purposes at least 1% of the blood should be dispersed or dissolved in the filtrate. After the blood has been heated until it has been denatured and dried to the desired extent, it is cooled to a temperature of less than 170 F., preferably less than 120 F. This terminates the denaturing operation. The cooling may be elfectuated in any suitable manner, as by expelling the blood mixture from the denaturing apparatus and permitting it to cool by depositing it in thin layers in air on a suitable support, by permitting it to flow a predetermined distance through air at substantially atmospheric temperature, or by passing it with agitation through a cylinder having a water cooled jacket.

The glue base obtained in this manner is granular and may contain a proportion of friable aggregates, resulting from the fusing together of the blood particles during the denaturing operation. The product may then be processed for disintegration of the aggregates into particles which are discrete and have but little tendency to stick to each other. Since it is substantially dry it may be stored for long periods of time and shipped to various plant locations without danger of degradation. Accordingly, it is ready for use as a glue base to which various glue-making agents may be added for the production of a glue having the desired properties.

Such agents, defined broadly herein as glue conditioning chemicals, comprise in general alkali metal caustic, including principally sodium hydroxide and potassium hydroxide; alkali metal silicates, including primarily sodium silicate, and lime or an equivalent material. A thermosetting resin also may be incorporated, depending upon whether a highly water-and-mold-resistant glue product is desired.

The denatured blood-filler mixture and the glue-making or conditioning chemicals are mixed together in the desired proportions together with the amount of water necessary for the production of a glue having the required consistency. Although the proportions of constituents in a given glue formulation are variable, in general they fall within the following broad range, proportions being expressed in parts by weight.

TABLE I General Preferred range range Blood 100 100 Filler 10-100 20-60 Water 300-1, 200 600-900 Alkali metal caustic 1-50 5-20 A glue having the above composition has decided adhesive characteristics and is suitable for some purposes. However, a better glue is obtained by the addition of other conditioning chemicals, i.e., alkali metal silicate and/or lime. Preferably both of these additional conditioning agents are included, in which case the glue will have the following formulation, proportions being expressed in parts by weight:

TABLE II General Preferred range range Blood 100 100 Filler 10-100 20-60 Water 300-1, 200 600-900 Alkali metal caustic l-50 5-20 Alkali metal silicate 10-400 20-100 Lime l-50 5-25 agitating the contents. The solid glue base comprising denatured blood and filler is added first with part of the water. Next, the alkali metal caustic dissolved in a predetermined amount of water is added with stirring.

Next the lime may be mixed with sufiicient water to disperse it and added with further stirring. Finally, the alkali metal silicate may be added in the form of its commercial water solution and thoroughly incorporated in the mix. The pine oil, or other anti-foaming agent, may be added at any suitable point in the procedure. Also, if filler is required in addition to that mixed with the blood prior to denaturing, it may be incorporated at a suitable point in the mixing procedure. After the constituents have been blended together thoroughly, the glue may be withdrawn from the mixer and is ready for application.

As has been indicated above, here also may be incorporated in the presently described glue, a thermosetting resin which makes the glue particularly useful in hot press operations, forming a strong bond, improving its handling properties, improving the water resistance of the glued product and improving its resistance to attack by micro-organisms such as bacteria, molds and fungi. The glues described herein are particularly well suited for use with such resins since the addition of the resin does not cause the glue mix to thicken and gel and become inapplicable on conventional glue Spreaders. This has been a problem widely encountered in the use of blood and other (e.g. soybean) glues containing thermosetting resins.

Furthermore, the use of the resin has the beneficial efieet of substantially improving the assembly e and spreadability of the glue. Still further, contrary to expectations, the thermal requirements of the glue, i.e., the amount of heat required to set it in a hot press operation, are not materially increased by the addition of the thermosetting resin.

The thermosetting resins which may be used together with the blood glues of the present invention comprise broadly the phenol-aldehyde resins as a class. Illustrative of such resins are the resinous condensation products of phenol and formaldehyde, the cresols and formaldehyde, resorcinol and formaldehyde, phenol and furfural and the like. These may be used in their usual commercial form, i.e., in the form of their aqueous solutions having a solids content of about 40% by weight.

The amount of thermosetting resin incorporated in the presently described glue may vary, for example, from about 'ten parts to about 1000 parts by weight (solids basis) of thermosetting resin per 100 parts of blood, the 0 constituents of the mix being employed in substantially the proportions set out above. The thermosetting resin may be incorporated at various stages of the mixing procedure, although it is preferred to add it after the caustic alkali has been added to the denatured blood glue base.

Thus, in this preferred procedure the blood may be denatured by the action of heat in admixture with a filler as indicated above. The denatured product then is cooled, if necessary, after which water, caustic soda, lime, sodium s i l igge ffller and an anti-foaming agent steam these materials being intimately mixed together to form a thick, grainy mixture. The phenolic resin then is added as an aqueous solution, if desired, and the mixing continued until the resin has been intimately dispersed throughout the glue mixture. The glue then is ready for application to the wood veneers or other objects to be glued together.

The glue mixtures prepared as described above may be applied in the plywood fabricating operation using the conventional glue spreaders and other equipment. Their application in such equipment is particularly easy because of their spreadability, stable viscosity, and non-gelling characteristics. Also, their consistency is such as to prevent excessive penetration into the wood veneers during the assembling operation, which increases the assembly time correspondingly. After applying the glue the veneefs may be assembled in the usual manner and pressed, either in the colgggss or in the hot pre particular composition employed'an the plywo lication contemplated.

The novel glues of the present invention and the process for their preparation are illustrated in the following examples wherein pants are expressed as parts by weight.

Example 1 100 parts of spray dried soluble blood and 45 parts of wood flour filler were mixed together. The resulting mixed powder had a moisture content of 9.75% dry basis. pounds of this powder was introduced into a horizontal steam jacketed, cylindrical heater, provided with means for stirring the powder and scraping it from the inner heated surface of the cylinder.

- The stirring and scraping mechanism was put into operation and steam at 115 p.s.i. (374 F.) passed through the jacket of the mixer. The temperature of the blood- 8 filler mixture within the heater was determined at intervals. After five minutes its temperature was 223 F., after eleven minutes it was 243 F., and after fifteen minutes it was 260 F. At the end of fifteen minutes a 4-pound sample was withdrawn from the heater and cooled rapidly by contact with atmospheric air to a level of below 120 F.

Example 2 Another sample of denatured blood glue base was obtained by continuing the heating operation described in Example 1 until a total heating time of 23 minutes had elapsed. At the end of this time the temperature of the blood-filler mixture within the heater had risen to 293 F. A sample was withdrawn at this temperature level and cooled to a temperature of below 120 F.

Example 3 Still another sample was obtained by continuing the heating operation of Example 1 until the total elapsed time of heating was 31 minutes. The heated mixture thereupon had reached a temperature of 310 F. A sample then was withdrawn from the heater and cooled to a temperature of below 120 F.

Example 4 Ten pounds of a mixture of spray dried soluble blood and wood flour in the same proportions as set forth in Example 1 was introduced into the heater described in that example. In this case temperature elevation of the sample occurred muchmore rapidly than in the preceding examples, because of the relatively small weight of blood mixture heated. At the end of five minutes heating, the temperature of the mixture had reached 276 F. and after nine minutes it had reached 304 F. Thereupon a sample was withdrawn and cooled below a temperature of 120 F.

Example 5 Thirty-five pounds of the dry soluble blood-wood flour mixture of Example 1 was introduced into the heater described in that example. Steam at 115 p.s.i. (347 F.) was introduced into the heater jacket. However, as soon as the temperature of the mixture had reached 218 to 227 F., the steam was applied intermittently as required to maintain this relatively low temperature range.

The contents of the heater then were heated at this temperature level for minutes, after which a sample was withdrawn and air cooled to a temperature of less than 120 F.

Example 6 The procedure of Example 5 was repeated with the exception that the steam pressure was applied in such a manner as to maintain the contents of the heater at a temperature of from 199 to 206 F. After minutes a sample was withdrawn and air cooled to a temperature of below F.

Example 7 Thirty-five pounds of the soluble blood-wood flour mixture of Example 1 was contemporaneously stirred and sprayed with water until the moisture content of the mixture, dry basis, had been adjusted to 15.7 by weight. The moist mixture was then introduced into the heater of Example 1 and treated in the manner described in that example. After six minutes of heating the temperature of the mixture had reached 226 'F., after fourteen minutes 277 F. A sample was then withdrawn and cooled rapidly to a value of less than 120 F. by contact with air at atmospheric temperature.

Example 8 100 parts of spray dried soluble blood was mixed with 38 parts of 325-mesh walnut shell flour. 36 pounds of the resulting mixture was introduced into the heater and treated as described in Example 1. The temperature of this mixture rose more rapidly than did the temperature physical structure. Each particle is essentially unchanged from its original shape as a result of heating but the nature of the components of the particle is changed. The outer or peripheral layer of the particle is affected by the heat and as a result of being subjected to heat is highly insoluble in alkaline solution. The portion of the particle internal of the peripheral layer is less aifected by the heat. The internal portion of the particle becomes waterinsoluble upon heating but is soluble in alkaline solution.

It has been observed that a particle of heat treated blood immersed in water only wets well but does not ap- 2o preciably swell or change its shape and that there is no coloration of the water which would evidence water solubility of the particle. On the other hand, it has been observed that, when a particle of the heat treated blood 10 denatured blood. They were fluid and not characterized by a dry graininess.

All of them were of superior spreading consistency, having viscosities within the broad range of to 500 5 poises, specifically 150 to 300 poises. In addition, their consistencies, handling properties and adhesive qualities were excellent, showing that in each case the blood had been denatured to about the same degree. All of them were superior for the gluing of plywood.

The results obtained using the glue base of Example 4, as compared with those obtained using that of Example 2, illustrate that the denaturing is more rapid at an elevated temperature. The application of the glue bases of Examples 5 and 6 illustrates that satisfactory denaturing can be accomplished at lower temperatures by prolonging the time of heating. Use of the glue base of Example 7 in the production of a satisfactory glue illustrates the acceleration of the denaturing rate by increasing the amount of moisture present.

Other glue formulations were made following the general procedure outlined above but using various glue conditioning chemicals in various proportions. These demonstrate the etiect of such variation and, in the case of Examples 15 and 16, illustrate the accommodation of is immersed in dilute sodium hydroxide solution the 25 the formula to suit glue bases made by procedures resultparticle swells rapidly and increases several fold in diameter. The outer layer of the particle becomes visible and ing in divergent degrees of denaturing. These were as follows:

Table III 1110 at Pine Powder Amt. KOH 50% Lime Silicate Visco- Ex. No. 65 F. oil of Ex powder in Hi0 NaOH in H1O Stir of soda Stir sity,

No. soln. polses has the appearance of a membrane at the blood-fluid interface and is capable of passing the sodium hydroxide solution. Upon continued contact with the alkaline solution the inner alkalisoluble portion of the blood, as an alkaline solution thereof, diffuses through the expanding membranous periphery of the particle and disperses throughout the sodium hydroxide solution. After about 5 The cooled powders of Examples l-8 were put individually through a grinder for disintegration of any lumps that had formed. Glues then were made using the powdered glue bases of Examples 2, 4, 5, 6, 7 and 8, as follows:

140 parts of the glue base was mixed with 890 parts water at 65 F. Five parts pine oil then was added. To this mixture was added 24 parts of 50% aqueous caustic soda solution and 14 parts hydrated lime suspended in 28 parts water. The resulting mixture was stirred for ten minutes and then 50 parts silicate of soda added and the stirring continued for another three minutes.

Plywood panels were made with the glues of Examples In each case the glue was spread uniformly on both surfaces of a .1 inch Douglas fir veneer at the rate of 125-130 lbs. of wet glue per thousand square feet of core veneer.

The core veneer with wet glue applied was laid between two other sheets of .1 inch Douglas fir veneer to assemble a 3-ply plywood panel, each ply consisting of .1 inch of Douglas veneer. Eighteen minutes after the glue was applied to the core veneer the panel assembly was put under a pressure of 200 psi. without heating. This pressure was maintained 'or ourteen mmu es.

At the end of this time sufficient bond was formed so that the panels could be handled. The panels were allowed to stand for six days in order to let the bond fully cure and then 20 one-inch shear strength test pieces were cut from each panel. Ten test pieces from each panel were sheared on a standard break machine and the shear strength and wool failure noted.

Also ten test pieces from each panel were soaked in water at F. for two days. Thereafter they were removed from the water, broken and again evaluated for shear strength and wood failure. In all cases substantial bonding of the veneers was obtained, even when the lime and/or sodium silicate were omitted. Markedly superior bonding was obtained however, when these glue conditioning agents were included.

Example 17 This example illustrates the application of the presently described blood glues in conjunction with a thermosetting The resulting glues contained soft swollen grains of phenolic resin.

Alknline earth metal carbonate A glue base was prepared according to the procedure of Example 2. It was formulated into a glue using the general procedure outlined in Example 9, except that after the addition of the sodium silicate 40 pounds of a liquid 50% solids phenol formaldehyde resin was added and the stirring continued for three minutes.

This glue was used in the manufacture of plywood using the same procedure outlined in Example 9, except 7 that the wet glue spread was reduced to approximately 80 lbs. per thousand square feet of core veneer. The panels were then hot pressed for three minutes in a press having platens heated to 260 F. The pressure on the panels was 200 lbs. per square inch. The resulting panels were tested for shear strength, wood failure, water resistance, and mold resistance, and found to be superior in all of these qualities.

When a mixture of denatured blood and a small proportion of extremely finely divided carbonate is used, this mixture is mixed with cellulosic filler and the glue making chemicals in the desired proportions together with the amount of water necessary for the production of a g ue having the required consistency. Although the proportions of constituents in a given glue are variable, in general they fall within the following broad range, proportions being expressed in parts by weight.

TABLE IV General range Preferred range Blood 100 0. -10 -100 Filler Water Alkali metal caustic TABLE v Preferred range Alkali metal silicate.-

Li me In addition .to the foregoing constituents, there may be included further components as previously described for mixtures of denatured blood and filler requiring larger proportions for eliective action.

Example 18 Thirty pounds of spray-dried soluble blood and 1.6 pounds (5.3% by weight) of precipitated calcium carbonate having a particle size of .04-.05 micron were intimately mixed together. The resulting mixed powder had a moisture content of approximately 8% dry basis. This powdery mixture was introduced into a horizontal, steam-jacketed, cylindrical heater provided with means for stirring the'powder and scraping it from the inner heated surface of the cylinder.

The stirring and scraping mechanism wasput into operation and steam at 115 psi. (347 F.) passed through the jacket of the mixer. The temperature of the bloodcalcium carbonate mixture within the heater was meas- 12 ured at predetermined time intervals, and samples withdrawn as follows:

Heating Temperature time F (minutes) Sample No attained) Heating Temperature time F. (minutes) attained) Sample No.

The samples were cooled to a temperature below 120 F. as soon as they had been withdrawn firom the heater.

The blood particles in each of samples 1-9 inclusive have the same unique physical structure described as set forth at the end of Example 8.

In this manner there was obtained a sequence of glue bases each of which was processed into a final glue by the addition of filler and glue conditioning chemicals, i.e., caustic soda and hydrated lime. The procedure was as follows:

The cooled mixtmes prepared as described above were ground individually for integration of any friable lumps that had been formed during the denaturing process. 100 parts of each mixture then was mixed with 30 parts of wood flour. To the resulting mixture there were added 8 to 25 parts water at 75 F. and 5 parts pine oil. 26 parts of a 50% aqueous solution of caustic soda and 13 parts hydrated lime suspended in 26 parts of water then were added in succession. The resulting mixture was stirred for five minutes after which 50 parts sodium silicate were added and the stirring continued for another three minutes.

The'glues produced by the foregoing procedure contained soft, swollen grains of denatured blood. They were fluid and not characterized by dry All of them were of superior strength and consistency, having visccsities the broad range of 40-500 poises, specifically -400 poises. Int-addition, their consistencies, handling properties, and adhesive qualities were excellent. All were superior for use in the gluing of plywood.

, Example 19 This example illustrates the application of the presently described blood glues in conjunction with a thermosetting phenolic resin.

A glue base was prepared according to the procedure of Example 1 wherein the heating was carried out for a total heating time of 12 minutes (sample No. 3). It was formulated into a glue using the general procedure outlined in Example 1, except that after the addition of the sodium silicate 40 parts of a liquid 50% solids phenol formaldehyde resin was added and the stirring continued for three minutes.

This glue was used in the manufacture of plywood using a glue spread of-approximately 80 lbs. per 1000 square feet of core veneer. The panels were then hot pressed for three minutes in a press having platens heated to 260 F. The pressure on the panels was 200 lbs. per

13 square inch. The resulting panels were tested for shear strength, wood failure, water resistance, and mold resistance, and found to be superior in all of these qualifies.

Accordingly, it will be apparent that by the present invention I have provided a novel blood glue and a process for making the same which are characterized by several advantages of the greatest significance. The glue is characterized by superior spreadability and high bonding strength. Its viscosity characteristics are such that a substantial proportion of water, at least 15% more than can be used with the glue disclosed in my aforesaid patent, Serial No. 461,947, may be employed in the formulation of the final glues. This cuts down the glue cost correspondingly.

In addition, the glue base may be prepared using relatively simple equipment in a rapid, efficient operation. When prepared it is stable and may be shipped dry to the plants where it is to be used. The glue then may be formulated at the plant without the use of elaborate equipment and highly skilled personnel. In this manner, substantial savings are achieved through lower transportation and labor costs.

Having thus described my invention in preferred embodiments,

I claim:

1. A dried, water-insoluble animal blood-solid particle, having an inner alkali-soluble portion within an outer alkali-insoluble membrane, the outer membrane being swellable in and permeable to alkaline solution and capable of passing an alkaline solution of the inner soluble portion therethrough.

2. A spray dried, water-insoluble animal blood-solids particle according to claim 1.

3. An adhesive component: water-insoluble animal blood-solids particles each having an inner alkali-soluble portion within an outer alkali-insoluble membrane, the outer membrane being swellable in and permeable to alkaline solution and capable of passing an alkaline solution of the inner soluble portion therethrough, said particles being swelled and dispersed and dissolved in aqueous, alkaline medium.

4. A glue base consisting essentially of a substantial portion of dried, water-insoluble, animal blood-solids particles, each of said particles having: an inner alkali-soluble port-ion within an outer alkali-insoluble membrane, the outer membrane being swellable and permeable to alkali metal hydroxide solution and capable of passing an alkaline solution of the inner soluble portion therethrough, and a solid filler in particle form.

5. A glue base according to claim 4 in which the dried, water insoluble, animal blood-solids particles derived from spray dried soluble blood particles.

6. A glue base as recited in claim 4 in which the References Cited in the file of this patent UNITED STATES PATENTS 1,976,436 Cone Oct. 9, 1934 2,292,624 Fawthrop Aug. 11, 1942 2,400,541 Cone May 21, 1946 2,620,280 Fencil et al. Dec. 2, 1952 ch the solid 7 

4. A GLUE BASE CONSISTING ESSENTIALLY OF A SUBSTANTIAL PORTION OF DRIED, WATER-INSOLUBLE, ANIMAL BLOOD-SOLID PARTICLES, EACH OF SAID PARTICLES HAVING: AN INNER ALKALI-SOLUBLE PORTION WITHIN AN OUTER ALKALI-INSOLUBLE MEMBRANE, THE OUTER MEMBRANCE BEING SWELLABLE AND PERMEABLE TO ALKALI METAL HYDROXIDE SOLUTION AND CAPABLE OF PASSING AN ALKALINE SOLUTION OF THE INNER SOLUBLE PORTION THERETHROUGH, AND A SOLID FILLER IN PARTICLE FORM.
 7. A GLUE BASE AS RECITIED IN CLAIM 4 IN WHICH THE SOLID FILLER IN PARTICLE FORM IS A CARBONATE IN POWDERY FORM SELECTED FROM THE GROUP CONSISTING OF CALCIUM, MAGNESIUM STRONTIUM AND BARIUM AND IS PRESENT IN AN AMOUNT BETWEEN 0.5 AND 10% BY WEIGHT BASED ON THE WEIGHT OF THE BLOODSOLIDS PARTICLES. 